【作者】 王秋霞；

【导师】 李立会；

【作者基本信息】 中国农业科学院 ， 作物种质资源学， 2012， 博士

【摘要】 小麦族包含23个基本基因组，其中H、P、St和Y基因组在小麦族中占有十分重要的地位。在小麦族中，携带H、P、St和Y基因组的植物主要包括大麦属（Hordeum L.，H）、冰草属（AgropyronGaertn., P）和假鹅观草属（Pseudoroegneria L., St）等的二倍体和同源多倍体物种，以及同时含有其中两个或三个基因组的鹅观草属（Roegneria C. Koch., StY）、偃麦草属（Elytrigia Desv., StE）、披碱草属（Elymus L., StHY or StH）和以礼草属（Kengyilia Yen et J.L Yang, StPY）的所有异源多倍体物种。本试验主要以含H、P、St和Y基因组的二倍体和多倍体物种及其属间和种间天然杂种为材料，利用分子细胞遗传学、反转录转座子LTR序列分析等方法，探讨物种进化过程中H、P、St和Y基因组间的遗传演化关系。获得的主要结果如下：1、首次建立了能够区分St、P和Y基因组的GISH/FISH技术，并以大颖草（Kengyiliagrandiglumis Keng，StStPPYY）居群内的5个单株为材料，对St、P和Y基因组核型结构进行了分析。发现各基因组染色体在不同单株间均表现出染色体结构上的多态性，且主要发生在染色体的端部；在3个基因组的所有染色体中，1P、1St、3St、1Y、2Y和3Y上的多态性最高。这些结果对于小麦族野生植物资源的收集、保存、研究与利用具有重要的理论指导意义。2、为了研究环境因子对多倍体化后St、P和Y基因组间重排的影响，利用双色GISH方法对采自9个不同生态环境的梭罗草（Kengyilia thoroldiana，StStPPYY）居群进行了分析。结果发现，在不同基因组间，染色体相对较大的P基因组与染色体相对较小的St和Y基因组间有异源易位的发生，其中P和Y基因组间的异源易位频率为22.22%， P和St基因组间的异源易位频率为8.15%；而染色体相对较小的St和Y基因组间没有异源易位的发生；在生态环境对异源易位的影响上，采自高寒山地和草原草场环境的居群异源易位频率显著高于谷底和湖盆环境的居群（P<0.05）；染色体易位类型和海拔高度间存在极显著的正相关（r=0.809, P<0.01），随着海拔高度的增加，居群的易位类型越复杂，说明自然环境在基因组的演化过程中发挥着重要作用。3、为了研究不同海拔高度对梭罗草物种P基因组内不同染色体参与异源易位的影响，对采自海拔4015m的居群Z2538和海拔4710m的居群Z2633进行了分析。结果显示，低海拔居群Z2538参与异源易位的是1P和7P染色体，而高海拔居群Z2633参与异源易位的是2P和5P染色体，进一步说明了自然环境对基因组不同染色体演化的影响是不同的。4、为了探讨多倍体物种的形成机理，以采自西藏的3个天然杂种为材料，分别命名为Ⅲ、Ⅳ和Ⅴ。根据育性，基因组构成，形态学和伴生植物结果综合推断，Ⅲ、Ⅳ为垂穗披碱草（Elymusnutans）和披碱草（Elymus dahuricus）间的天然杂种，Ⅴ为垂穗披碱草和短颖鹅观草（Roegneriabreviglumis）间的天然杂种。分子细胞遗传学分析发现，Ⅲ、Ⅳ为六倍体，各含有7条异源易位染色体；Ⅴ为五倍体，含有6条异源易位染色体；多价体主要是由非同源染色体St和Y配对形成或者是由大片段异源易位染色体形成；尽管3个天然杂种的平均c值间没有显著差异（P>0.05），但在基因组间，St-Y的c值显著高于St-H和H-Y,说明这3个基因组中St和Y基因组间具有较近的亲缘关系，这对探讨Y基因组的起源演化具有重要意义。进一步的分析表明，多倍体物种的形成不是通过一次简单的天然杂交、加倍形成的，而是一个复杂的网状进化过程，并通过不同基因组间不同染色体的结构重排并逐步达到遗传平衡后才能成为一个稳定的新物种。5、采用含H、P和St基因组的二倍体和同源多倍体，含St、Y基因组的异源多倍体，以及短柄草物种为材料，利用反转录转座子LTR序列进行分子系统发育和拷贝数多态性分析发现，H、P、St和Y这4个基因组间都存在一定的同源关系，这为进一步探讨小麦族不同基因组的遗传演化提供了一定的分子生物学基础。更多还原

【Abstract】 There are23basic genomes in the tribe Triticeae, and the H, P, St, and Y genomes are importantgenomes of this group. The H, P, St, and Y genomes in Triticeae are mainly found in some diploid andautopolyploid species, for example, Hordeum L.(H genome), Agropyron Gaertn.(P genome),Pseudoroegneria L.(St genome), and some allopolyploid species, for eaxmple, Roegneria C. Koch.(StYgenomes), Elytrigia Desv.(StE genomes), Elymus L.(StH or StHY genomes), and Kengyilia Yen et J.LYang (StPY genomes). In order to study the genetic evolution relationship among H, P, St, and Ygenomes, some diploid and polyploid species including H, P, St, and Y genomes, and their naturalhybrids were ananlyzed in our study using molecular cytogenetics, LTR sequeces analysis ofretrotransposons and so on. The main results as follows:1. A GISH-FISH method was first developed to distinguish the St, P, and Y genomes, and thekaryotypes of five individuals from population Z1925of Kengyilia grandiglumis Keng (2n=6x=42,StStPPYY) were analyzed. The results showed that there were structural polymorphisms in all of thechromosomes from the three individual genomes. The polymorphisms were mainly found in theterminal regions of chromosomes, and infrequently near the centromeric region. Of all thechromosomes,1P,1St,1Y,2Y,3St and3Y showed the highest polymorphisms. The polymorphismswithin the individual chromosomal structures provided important guidance on the collection,preservation, study and utilization of wild species in Triticeae.2. To investigate intergenomic rearrangements after polyploidization of Triticeae species and todetermine the effects of environmental factors on them, nine populations of a typical polyploid Triticeaespecies, Kengyilia thoroldiana (Keng) J.L.Yang et al.(2n=6x=42, StStPPYY), collected from differentenvironments, were studied using genome in situ hybridization (GISH). We found that intergenomicrearrangements occurred between the relatively large P genome and the small genomes, St (8.15%) andY (22.22%), in polyploid species via various types of translocations compared to their diploidprogenitors. However, no translocation was found between the relatively small St and Y chromosomes.Environmental factors may affect rearrangements among the three genomes. Chromosometranslocations were significantly more frequent in populations from cold alpine and grasslandenvironments than in populations from valley and lake-basin habitats (P<0.05). There is a significantpositive correlation between types of chromosome translocations and altitude (r=0.809, P<0.01). Thetypes of chromosomal translocations become more complex with increasing altitude, which indicatedthat environment play an important role in genome evolution.3. To investigate the effects of different altitudes on different P chromosomes involving inintergenomic translocations in K. thoroldiana, the two populations Z2538from4015m and Z2633from4710m were analyzed in our study. The results showed that P chromosomes involving in intergenomictranslocations are1P and7P chromosomes in population Z2538, while2P and5P chromosomes inpopulation Z2633, which indicated that the effects of environment on different chromosomes evolution of the same genome were different.4. To discuss formation mechanisms of polyploid species, three natural hybrids collected inTibet, which were named Ⅲ, Ⅳ, and Ⅴ, were studied. Based on the fertility, genomes constitute, andmorphology and their accompanied species, it was inferred that Ⅲ and Ⅳ were natrual hybrids betweenElymus nutans and Elymus dahuricus, and hybrid Ⅴ was natrual hybrid between Elymus nutans andRoegneria breviglumis (2n=28, StStYY). Ⅲ and Ⅳ were hexaploids hybrids including7translocationchromosomes separately, and hybrid Ⅴ was pentaploid hybrid including6translocation chromosomesusing cytogenetics. Multivalent was mainly formed by St-Y chromosomes or large fragmenttranslocation chromosomes respectively. Although there were no significant differences among themean c values of these three hybrids (P>0.05), the c value of (St-Y) genomes was significantly higherthan that of (St-H),(H-Y), so closest relationship occur between St and Y genomes among the threegenomes, which is significant for study the origin and evolution of Y genome. The further analysissuggested that polyploid species become a stable and new species not by only one simple natrualhybridization and chromosomes doubling, but complex reticulate evolution.5. Some diploid and polyploid species including H, P, St, and Y genomes, allopolyploid speciesincluding St and Y genomes, and Brachypodium sylvaticum were used as materials and studied bymolecular phylogenetic analysis and copy numbers variation of LTR sequeces of retrotransposons. Wefound that some relationhip occurred among H, P, St, and Y genomes, which provided molecularbiology basis for further research on genetic evolution of different genome in Triticeae.更多还原